Allyl alcohol is used commercially for the manufacture of 1,4-butanediol (see, to for example, U.S. Pat. No. 4,215,077). It is also used as a hydroxyl functional monomer in the polymer industry (see, for example, U.S. Pat. No. 5,444,141).
Allyl alcohol can be produced by the isomerization of propylene oxide (PO). PO isomerization can be performed by a slurry-phase process (see for example, U.S. Pat. No. 3,274,121) or by a gas-phase process (see, e.g., U.S. Pat. No. 3,044,850).
Isomerization is typically performed in the presence of a lithium phosphate catalyst. The preparation of lithium phosphate catalysts is well known in the art. U.S. Pat. No. 2,426,264 teaches preparing the catalyst by precipitating a crude lithium phosphate from the mixture of an aqueous solution that contains phosphate ions and an aqueous solution that contains lithium ions. The crude precipitate is then washed with water and dried to form catalyst powder.
Methods for improving lithium phosphate catalysts are known. U.S. Pat. No. 2,986,585 teaches adding alkali metal hydroxides such as sodium hydroxide and potassium hydroxide during the precipitation of lithium phosphate. The resultant catalyst has improved activity and selectivity for allyl alcohol production. U.S. Pat. No. 6,803,491 teaches a further improvement to lithium phosphate catalysts, which comprises precipitating a lithium phosphate from a mixture comprising a first aqueous solution containing lithium and sodium ions and a second aqueous solution containing phosphate and borate ions. The resultant lithium phosphate catalyst has increased activity and selectivity in the isomerization of an alkylene oxide to the corresponding allylic alcohol. The lithium phosphate catalyst is taught to preferably contain from about 0.01 wt. % to about 1 wt. % of sodium, more preferably from about 0.02 wt. % to about 0.8 wt. % of sodium.
As with any chemical process, it is desirable to attain still further improvements in the PO isomerization process. We have discovered a new process for the production of allyl alcohol.